[Bldg-rate] [Bldg-sim] District Thermal System

[Eric Youngson]

David,
	My question relates to step 1 only. My is that step 1 is not
requiring identical purchased heat for both cases. It in fact states
that the Proposed building should modeled "As Designed" while the
Baseline building is per Appx G except for heating type energy source
(Table 3, p.6).
	I'm not sure if I'm interpreting this correctly. It seems, as
you stated in the previous reply, that the intent is to hold heating
energy neutral, but the way it is stated is 'COST neutral'--not energy
neutral (Table 1, p.4 - EAc1, Step 1).

Eric

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of David S
Eldridge
Sent: Tuesday, September 09, 2008 10:34 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] District Thermal System

I'm not sure if I'm quite following the question, but let me see if this
is what you are looking for, specifically for your case of a district
energy central heating plant and stand-alone cooling:

Step 1:  identical purchased heat for both cases, chiller vs DX per
system selection tables in App G.  Yes this may handicap you if the cost
for purchased heat is relatively high (rightly so?).  If you make two
points you may choose to stop here.  Reaching 14% may require an
aggressive envelope, lighting and distribution systems.  The DX vs
chiller comparison may also help in your case.

Step 2:  if you think your distributed energy heating plant is
relatively efficient compared to 90.1, compare a virtual model of the
DES with a stand-alone boiler system per App G.  In your case if I'm
understanding correctly, the cooling systems will be the same DX vs
chiller in step 1 and step 2.

How is this different than before?  If your central plant is very
efficient, you are able to take some credits for it in step 2, which you
couldn't have done under App G alone.  If your central plant is less
efficient, then you are in basically the same case as you would have
been all along comparing purchased heating options in step 1.  It's not
any more penalizing than before in terms of the purchased heating.

David


>
> Thanks Paul,
>         I guess I was just stating that the comparisons on equipment
are
> not so direct when you have one source from a DES system. Also, I'm
not
> really sure if I'm interpreting correctly that the DES being modeled
in
> the proposed but not in the baseline is fitting the intent of holding
> the upstream equipment cost neutral. I suppose that it is as long as
the
> heating source is separately metered and the rate applied is the same.
>
> Thanks,
>
> Eric
>
> -----Original Message-----
> From: Paul Riemer [mailto:Paul.Riemer at dunhameng.com]
> Sent: Tuesday, September 09, 2008 9:55 AM
> To: Eric Youngson
> Subject: RE: Re: [Bldg-sim] District Thermal System
>
> Eric,
> You stated you were using campus steam but I don't quite follow the
last
> paragraph or what you are doing on cooling.
>
> If you are installing a chiller in & for your building, yes the tables
> G3.1.1A & B stand and you might have chiller versus DX in both Step 1
> and Step 2.
>
> If you are using campus chilled water then step 1 has both models with
> purchased chilled water and step 2 has your campus system versus the
> Table G3.1.1A & B system.
>
> There is an ASHRAE 90.1 addenda that you can elect to follow that
> changes the crossover points for Table G3.1.1A.  You may want to track
> that down but I would guess it might save you some effort at the cost
of
> reduced savings.
>
> I agree the new document generally makes it harder to show the 14%
> savings.
>
> Good luck,
> Paul
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Eric
> Youngson
> Sent: Tuesday, September 09, 2008 11:40 AM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] District Thermal System
>
> Sim List,
>         I'm simulating a LEED DES model of a campus central steam
plant.
> Under the new requirements discussed below specifically addressing
'step
> 1'. The way that I read the document, step 1 requires that the
"upstream
> equipment [be] modeled as COST neutral" (Table 1, p.4) while the
> baseline DES system is compared with a proposed system "As Designed"
> (Table 3, p.6) which suggests that the upstream DES equipment
(including
> its inefficiencies) shall be modeled in the proposed building for step
> 1.
>         If I am reading this correctly, it would be much more
difficult
> to acquire the required 2 points for certification (14% - NC) than
> previously suggested.
>         Also, the comparison for systems not directly affected by the
> DES central plant (chiller in my case) is not necessarily a direct
> comparison. My building is ~75,000 SF & 3 floors (fossil fuel /
> purchased heat), therefore according to Table G3.1.1A & B my baseline
is
> system 5 Packaged VAV w/Reheat - cooling type: direct expansion.
>
> Any and all thoughts on this topic are welcome
>
> Thanks
>
> Eric
>
>
>
> -----Original Message-----
> From: bldg-sim-bounces at lists.onebuilding.org
> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of David S
> Eldridge
> Sent: Thursday, August 07, 2008 9:02 AM
> To: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] District Thermal System
>
> It seems that the intention here is that if a credit is taken for an
> exemplary LEED building for energy efficiency, it will have to
overcome
> district energy system (DES) inefficiencies if they are present.  But
at
> the same time, you are able to get the minimum two EAC1 credits, to
some
> degree regardless of how bad the DES performs - so not excluding most
> projects, but limiting the options for those projects with inefficient
> infrastructures.  This recognizes some of the constraints that a
campus
> project might encounter.
>
> Likewise an efficient DES that may have efficient equipment,
> cogeneration, heat recovery or other efficiencies will benefit the
LEED
> project and the team is rewarded for having built onto this type of
> system.
>
>
> Step 1:  Building stand-alone scenario - for EAP2 compliance as well
as
> documenting up to two EAC1 credits.  In both cases will be purchased
> from district energy systems for heating and cooling as appropriate.
> This I think was the discrepancy between Fred and Julia's posts - the
> USGBC document states on page 8 that the actual prices are to be used,
> so it would include the overhead and profit components for a
commercial
> DES.  For campus situations without a "price" you must calculate the
> equivalent value and it isn't specified if this includes the overhead
> components.
>
> If your building used DES for only one source, then the other source
> would be modeled as proposed with the baseline equipment per App G.
>
> So as Fred mentioned, it will be DES vs DES, chiller vs chiller, or
> boiler vs boiler, etc.
>
> If only pursuing EAP2 and two or fewer EAC1 credits (and achieving
> them?), stop here.
>
>
> Step 2:  Aggregate building - for pursuit of additional EAC1 credits -
> here the DES will be modeled for electricity and fuel usage, and
> compared to a building with baseline heating and cooling equipment per
> App G.
>
> The key point of the text is "virtual on-site equipment representing
> upstream" systems.  So not exactly that system, but representing the
> LEED project's share of that system.
>
> Putting some numbers to a cooling plant for example purposes, the
> intention is not for you to model a 500 ton load building being served
> by a plant with four 5,000 ton chillers.  Neither is the intention
that
> you should model the other buildings making up the 19,500 ton
> difference.
>
> The simulation programs are generally able to use efficiency
> calculations based on the total plant, but imposed on a theoretical
> smaller "virtual" plant serving the load of the new project.  This is
a
> reasonable approximation to the share of the plant energy for the new
> project assuming the cooling/heating loads are following the profile
of
> the DES in general.  The virtual 500 ton chiller will have capacity
> specified to match the LEED project's demand, but with the efficiency
> curves and EIR of the existing 5,000 ton chillers.
>
> Obviously the capacity of everything in the plant would have to be
> adjusted, not just the chillers and boilers - include pumps, cooling
> towers, etc.
>
> There is a statement about Step 2 only providing up to four additional
> EAC1 credits over Step 1, up to a maximum total of ten credits (like
> normal).  But my interpretation of the document is that even if you
> documented six EAC1 credits in step 1, you can only claim two of them
> unless you unlocked that potential by proceeding to Step 2.  Is this
> everyone else's interpretation also?
>
> Hope this helps!
>
> David
>
>
>
>
> > -----Original Message-----
> > From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-
> > bounces at lists.onebuilding.org] On Behalf Of Craig Simmons
> > Sent: Thursday, August 07, 2008 8:47 AM
> > To: bldg-sim at lists.onebuilding.org
> > Subject: Re: [Bldg-sim] District Thermal System
> >
> > Hi May,
> >
> > I interpret the update differently. It does not state that the
> capacity
> > must
> > be the same, only that the efficiencies must be the same. I believe
it
> is
> > expected that you create a virtual onsite plant sized to replace the
> loads
> > normally covered by the DES. The virtual plant must have the same
> > efficiencies as the actual plant, but not the same capacity.  In
> addition
> > you must implement a calculation or approximation to account for
> losses in
> > the distribution system. I believe that the statement "the DES
central
> > plant
> > itself shall always be modeled as a total, entire unit" is to
prevent
> the
> > model from combining the virtual plant (to cover DES loads) with any
> > supplementary onsite plants that may exist. I don't think it is
> intended
> > that you model the DES at its actual capacity.
> >
> > Anyone else have a different opinion?
> >
> > Craig Simmons
> >
> > The Green Engineer, LLP
> > Sustainable Design Consulting
> > 50 Beharrell Street
> > Concord, MA 01742
> > t: 978/369-8978
> > craig at greenengineer.com
> > www.greenengineer.com
> >
> > Please consider the environment before printing this email. Thank
you.
> >
> >
> >
> > -----Original Message-----
> > From: May Xu [mailto:may.xu at hok.com]
> > Sent: Tuesday, August 05, 2008 10:20 PM
> > To: Jeff Haberl; bldg-sim at lists.onebuilding.org
> > Subject: Re: [Bldg-sim] District Thermal System
> >
> > Hi Jeff,
> >
> > Thanks, I found many useful information there, it is a very good
> > resource! However, I didn't get relative answers regarding my
> question,
> > which is about the simulation rule updated by USGBC recently about
the
> > district thermal system. Could anyone give me any suggestions?
> >
> > Thanks a lot!
> >
> > May
> >
> > -----Original Message-----
> > From: Jeff Haberl [mailto:jeffhaberl at tees.tamus.edu]
> > Sent: Tuesday, August 05, 2008 11:36 AM
> > To: May Xu; bldg-sim at lists.onebuilding.org
> > Subject: RE: [Bldg-sim] District Thermal System
> >
> > May:
> >
> > The Laboratory has spent quite a bit of time modeling the thermal
> plant
> > on the Texas A&M Campus with good success. Unfortunately, we ended
up
> > using some rather complex, interacting loop models with chiller
> on/off,
> > staging algorithms, etc.
> >
> > We have a number of papers and thesis on this at our web site
> > "www-esl.tamu.edu" look under publications.
> >
> > Jeff
> >
> > 8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) :=') 8=) 8=) 8=?
> > Jeff S. Haberl, Ph.D.,
> > P.E.............................jhaberl at esl.tamu.edu
> >
Professor......................................................Office
> > Ph: 979-845-6507
> > Department of Architecture.......................Lab Ph:
979-845-6065
> > Energy Systems Laboratory.......................FAX: 979-862-2457
> > Texas A&M University..............................77843-3581
> > College Station, Texas, USA.......................URL:
> www-esl.tamu.edu
> > 8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) 8=? 8=) 8=) 8=)
> >
> > ________________________________
> >
> > From: bldg-sim-bounces at lists.onebuilding.org on behalf of May Xu
> > Sent: Mon 8/4/2008 4:53 AM
> > To: bldg-sim at lists.onebuilding.org
> > Subject: [Bldg-sim] District Thermal System
> >
> >
> >
> > Dear All,
> >
> >
> >
> > I'm now working on a project using Districted Heating System
provided
> by
> > a municipal system. The municipal system is working for a very large
> > areas providing steam for about hundred buildings. And my building
is
> > one of them.
> >
> >
> >
> > According to the latest update issued by USGBC
> > (https://www.usgbc.org/ShowFile.aspx?DocumentID=4176), the modeling
> will
> > be implemented by two steps. My question is about Step-2 (Aggregate
> > Building/DES Scenario).  In step-2, the energy source of Proposed
> > Building is virtual on-site chiller representing upstream DC system.
> The
> > document also issues "The DES central plant itself shall always be
> > modeled as a total, entire unit." My understanding is that it
requires
> > to model the central plant with the full capacity that is able to
> > provide heating for all of buildings in whole district. However, if
> > doing so, the energy consumption of the proposed building may be
quite
> > quite high, since it includes the energy consumption of the whole
> > heating plant!! But my building is only one of the 100 buildings
that
> > are heated by the central plant.  It is weird and  I don't think it
is
> > what USGBC asked for. Does anyone know what shall I do for the
> proposed
> > building in Step-2?
> >
> >
> >
> > Thank you.
> >
> > May Xu,  LEED(r)AP
> > Project Engineer - Sustainable Design
> >
> > HOK
> > Suite 3705A, Ciro` s Plaza,
> > 388 Nan Jing West Road,
> > Shanghai, 200003, PRC
> >
> > Tel:  (86 21) 6334.6181 ext. 2230
> > Fax: (86 21) 6334.6182
> >
> >
> >
> > www.hok.com <http://www.hok.com/>
> > www.hokasiapacific.com <http://www.hokasiapacific.com/>
> >
> > Please consider the environment when printing this email.
> > This email message is for the sole use of the intended recipient(s)
> and
> > may contain proprietary and/or confidential information. Any
> > unauthorized review, use, disclosure or distribution is prohibited.
> If
> > you are not the intended recipient, please contact the sender by
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> > email and destroy all copies of the original message. Thank you .
> >
> >
> >
> >
> >
> >
> >
> >
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